Motor-control system.



M, WHITING, MOTOR CONTROL SYSTEM.

Ammunition* FILED JAN. 1s, 191s.

Patente@ Apr. 2, 19M

UNITED sTATlas @nur orrIoE.

MAXKA. WHITING, OF SCHENECTADY, NEWT YORK, ASSIGNOR TO GENERAL ELECTRICCOMPANY, fr CGRPOBTION 0F YCERK.

MOTOR-CONTR'QL SYSTEM.

Specification. of ietters PatentA Fatcnterl Apr. 21, 1914.

Application filed. January 18, 1913. Serial No. "ig

To all whom it "may concer/i Be it known that I, MAX A. lViriTiNc, acitizenof the United States, residing at Schenectady, county of'Schenectady,l State of New York,` have invented certain new and lusefulImprovements in Motor-Control Syst-ems, of which the following is aspecifirunning', or While the apparatus is in an infio operativecondition. o

vMy invention relates more specifically to theprovision of means wherebyprotection against the occurrence of overload conditions is afforded toan electric motor and its control apparatus.

In the start-in ofelectric motors by the use of successive y actuatingcontaetors for cuttinA out starting resistance under the control vo amaster controller, it is common to employ a circuit breaker' which willopen upon thekoccurrence ci. abnormal circuit conditions. Thearrangement is usually such that When the circuit breaker is opened itwill automatically close or reset only when the master controller isreturned to oli' po sition. lVhen the maste' controller is in the oilposit-ion and the line switches are left closed one side of the line isstill closed at the circuit breaker although the motor cir-4 cuit isopen. Under these conditions a. dangerous short circuit may be caused bygrounding of the wirin One of the objects o my invention is to providemeans whereby upon the occurrence of such conditions the circuit breakerwill open uand remain. open until the operator moves the masterycontroller to start the rotor.

In carrying out my invention I employ a circuit breaker which iselectroniagnetically closed upon the closing of one of the contactorsfor starting the motor, preferably the first contacter of the series.An. overload relay having an overload coil' on each side of the line isprovided which opens circuit breaker upon the occurrence of an overloadupon the circuit and can only be closed in ster controller to olfposition. It is not s'uilicient, therefore, to simply return the mastercontroller to oil' position order to close the circuit breaker, but afurther step, must be taken, namely, the master controller muet be movedto operative position so as to close one of the contactors, since thecircuit breaker can only he closed upon the closing; of such contacter'.By this arrangement the circuit breaker 'will notA ordinarily open whenthe master cou- 'troller is moved to olli position 4but if an overloadshould occur at that time the circuit breaker will open so as tocompletely cut the motor from the line, and the circuit breaker cannothe again closed until the overload is removed and the master con trolleris niovcddo close one of the contactors,

Other objects and purposes of my inven tion will appear in the course ofthe iollowing specification which .l have disclosed my inventionembodied in concrete form for purposes or" illustration.

Referring to the accompanying drawing illustrating my invention, .Arepresents the armature and F the field of an electric mctor to becontrolled. have shown this motor of the series type tor purposes ofillustre, ion, although it is obvious thatr my in.- ventioii is in nosense limited to this type of motor. R and R2 represent three sectionsof resistance for starting this motor by being successively cut outl ofcircuit..

7i and f5 represent tivo line contactors for closing the motor circuit.for operating in -provided for automatically cutting' out the sectionsoi resistance R, lt and R2. lVhen the contactors .f and f' are closed,for in* stance5 the current will pass from the p ositive side of theline through the switch S through one oi the overload coils 13hcrcinciter referred to, through the contact of the contacter f,conductor le, armature A, rer-:stance R2, R', through the Winding of Cfr-the contacter l0, resista-nce R through contacts of the cont-actors f",conductor l5, field l?, thro-ugh the contacts of the circuit breaker CB,hereinafter referred to, and back to line through the other overloadcoil 13. The contact-ors l0, ll and l2 are represented here as of theseries type disclosed in the Murphy application, Serial No. 608,652, thecharacteristic feature of which is that the contactors do not close whenthe current is high, but do close when the current drops to apredetermined value. Upon the rush of current due to the closing of themotor circuit, therefore the contacter 10 will not be closed until thecurrent is reduced by the speeding up of the motor armature. and thenthe contacter 10 will close and short circuit the section of resistanceR through the Winding of contacter ll. In like manner the sections ofresistance R and R will be sucessively cut out oli circuit. `Theoperation of these contactors forms no part of my invention and it issuliieient therefore to say that when the motor is up to running speedlthe resistance sections are all eut out and 'the contactors 10 and 11are opened leaving only the contactsof contacter' 12 closed with theWinding of this contacter in series with the contacts.

As thus far described the arrangement is of the type now Well known andoperates in a. ivell known manner. ln order, however, to open the motorcircuit upon the occnrrence of an overload l have provided a circuit'breaker CB. This circuit breaker as shown is of the contacter type andisclosed lnthe lWinding 16 just the saine as'the ordinary contacter. Itwillsiie noted that the Winding of the circuit bre-alter will beenergir/,cd only through the interlocking contacts ri' or 1S upon theline contacter-s 7" and f respectively. In order that these line cont;et( "s shall close it is iii-st necessary that the overload relay shallhe closed or set. This overload relay as illustrated in the drawingconsists ci? a triple pole switch having the stationary contacts 19, 2Oand Qi., two of which, 19 and Q0, are in engagement with the movable sqtch arms when the relay is closed, While the latter contact :2l is inengagement with its movable switch arin when the rela is open. Therelayis closed by the. coil 22 W Lich is shown conventionally in thedrawing as having a plunger 23 which rises when its coil is energized soas to engage the projection 'i2/t and move the overload coil. to closedposition, at the same time breaking` the circuit of the Winding 522 atthe contact 2i. 1When either or both of :he overload coils 13 isenergized above a determined value, the operating inschainsni, shownconventionally as consisting of a rol 25 having upon it the course forthe coils; i3 is so arranged that `when it rises it engages a.projection QG, which moves the im l aecomo relay to open position asshown in the drawv ing. The specific construction of this relay forms nopart of my invention and it is to be understood that it is shown merelyin a diagrammatic Way for purposes of illus-- tration. As illustrated,the relay contacts are not moved throughout their range of movement bythe coil but are moved by the Weight 27 which carries the switch toproper position in either direction after it has been moved over centerby the plungers of Vthe coils.

The arrangement of circuits and mode of operation of my device are asfollows: Assuming that the parts are Ein the position shown in thedrawing and the line switch S is closed, the actuating Winding 22 of theoverload relay will immediately be energized, the circuit being from thepositive side of the line, through the Wire Q9, through the contacts ofthe master controller, which is in the eil position, ,vireZS, contact iland coil 22 to the negative side of the line. This Will move the relayto the closed or set position and denergize the actuating coil 22. lfnow the master controller is moved -in either direction, as, forinstance, into the position ,FL for forward movement, the

contacto "s jf' and f will be closed as before,

described. The closing of the contacter 'f' completes a circuit throughthe actuating winding 16 oi' the circuit breaker CB, the circuit beingas follows: F rom the positive side of the line to the Contact 19 of theoverload `gelay, thence through wire 28"'to the master controller, Wire30, interlock 18, Winding 16,4 to the other side of the line. Thecircuit breaker now closes and the motor Will start and come up torunning speed by cutting out sections of starting resistance as abovedescribed. 'In lilie manner, if the master controller is moved to thereverse position r1, the contacter-s o* and 7" will be closed to startthe motor in the reverse di rection. vThe circuit breaker will then beelosedithrough the interlock l? on 'the con taeter r. if, now, during;norinal runnir, an overload Occurs on the line the overioad relay vvillhe moved to the position shown in the drawing, thereby opening thecircuit breaker and the line contactors and stopping the motor. In orderto again start the motor the master controller must be brought bach tothe oli' position as it is only in this position that the Winding 22 canbe energized to again close or reset the overload re lay. Assume,however, that While the motor is normally running the master controllerniovedhack to the oil position with the overload relay in its rclosedposition, since no overload has occurred to open it. .Vhco. the mastercontroller is moved to oil' position the line contactors which happen tobe closed will be opened since the circuits oi their energizing windingswill be opened at the contac-ts of the master controller. The circuitbreaker., however. is not opened.

It will be noted that While the actuating circuit of the circuit breakerpasses through the interlocks on the line contactors, there is amaintaining circuit for the circuit: breaker which is closed at theinterlock 531 on the circuit breaker, this maintaining circuit being asfollows: From the positive side of the line, through the contact 19 ofthe overload relay, contact 20. wire interlock 31, winding' 16 of the.circuit breaker, back to the other side of the line. The circuit breakerwill therefore remain closed as long; as the overload relay is in itsclosed position. ll/hilo the motor stopped so longA as the switch S isclosed, there is danger of overload occurring due to grounds or othercauses, since only one siuc of the line is opened. lf such an overloadshould occur, the overload relay will be moved to open position, therebyopening the. circuit breaker and completely cutting otl the motor. l`11rtlierinore, the return of normal conditions is not sutlicient toclose the Acircuit breaker although it will `close the overload relay.ln order to close the circuit breaker it is necessary that the mastercontroller 1oe moved to operative position soas to close one of the linecontaetors or r since the circuit breaker can only be closed through oneof the interloeks 1? and 18 on these contactors. T his insures that uponthe appearance of such an overloadthe circuit-breaker will immediatelyopen and will not close againuntil the operator arrives to remove thecause of the trouble and start the motor.

`While I have described niiy invention as embodied in concrete form andopt-ratingl in a specific manner in accor-nance with the provisions ofthe patent statutes, it should be understood that 1 do not limit myinyention to the speciiic arrangement herein disclosed since variousmodilicati'ons thereof will suo'- gest themselves to those skilled inthe art uithout departing from the spirit ot my invention, the scope ofwhich is set forth in thc annexed claims.

What 1 claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. r1`he combination with an electric motor, of a controller therefor,an ov rload re-.

lay having an actuating coil on each side of the supply circuit andarranged. to close in the ott' position of said controller, and a.circuit breaker electromagnetically closed upon the movement of thecontroller' to operative position and controlled by said relay.

2. The combination with an electric motor. ot' a controller therefor, anoverload. re lay having an overload coil on each side ol the supplycircuiti arranged to he electromagnetically closed in the otf positionoil said controller, a circuit breaker having; an actuating windingwhich is energized upon the movement oi' the controller to operativeposition, and a mainte.ining` circuit con* trolled by said relay.

The combination with an electric motor, of a controller therefor, anoverload relay arranged to be closed in the oit' position of saidcontroller', and a circuit breaker hav` ingan actuating circuit which isenergized upon the movement o1a the controller to oper atire position,and maintaining circuit controlled by said relay.

li. The combination with an electric motor, of a contacter forcontrolling the circuitthereof, a, master controller therefor7 anoverload relay arranged to be closed in the oli" position ot the mastercontroller for controlling the circuit of said contacter, and circuitbreaker haring' an actuating circuit which is energized upon the closingof said contacter and a maintaining circuit controlled by said relay.

5. The combination with an electric mo tor, of a plurality ofconsecutively operating contactors Vtor controlling the circuit thereof,a master controller therefor, an overload relay arranged to loe closedin the oil' position of said .master controller for controlling theoliieration of said contactors, and a circuit breaker having anactuating circuit'. which is energized upon the closing` or the first ofthe contractors, and a maintaining circuit controlled by said relay.

The combination with an electric'motor, of a plurality of consecutivelyoperating contactors for controlling the circuit thereof, a mastercontroller therefor, an overload relay having an overload coil-on cachside ofthe supply circuit, electromagnetic means for closing the saidrelay in the od position of the master controller to control. theoperation of the said contactors and a circuit breaker having anactuating ircuit which is energized upon the closing of the .first ofsaid contat-tors, and a maintaining circuit controlled by said relay.

In Witness whereof, I have, hereunto set my hand this 16th day ofJanuary, 1913,

MAX ri. WHITING. `Witnesses BENJAMIN B; HULL, HELEN Onrono.

